INVESTIGATING THE SOURCES OF GROUNDWATER FEEDING THE HUNTSDALE STATE FISH HATCHERY, CUMBERLAND COUNTY, PENNSYLVANIA

Constructed in 1932 on the site of a watercress farm (in a village with so many spring-fed streams it was once called Mill Town), the Huntsdale State Fish Hatchery is one of the largest in PA, rearing over one million cold, cool, and warm water fishes annually. From its earliest operations, it has been hailed as producing perhaps the fastest fish growth and brightest coloration of any hatchery known to the PA Fish Commission. The ability to raise diverse species, the rapid growth of fish and overall hatchery success are attributable to the waters feeding the hatchery. These include at least 15 springs and a stream draining nearby South Mountain (itself spring fed at high elevation). Despite their importance to the hatchery operation, the springs are not well characterized geochemically or physically. Together, the springs discharge an average of 7,000 gpm (442 l/s) within a range of 3,500 gpm (220 l/s) to 9,000 gpm (568 l/s), and do not become turbid even after major precipitation events. Despite all springs occurring on less than 100 acres (41 ha), they have differing (some non-overlapping) chemical and physical properties. We have completed (so far) four rounds of sampling and have characterized the springs based on physico-chemical, major and trace element chemistry, isotopic and fluorescence signatures. The spring signatures cluster in groups that are not always closely related to their geographic proximity. Instead, rather distant springs show similar signatures indicating that they are probably fed by the same components of the local karst system. Early records note that several of the springs when used singly to rear fish had high, if not complete, mortality. However, mixing of the waters and intense aeration quickly produced the remarkable growing conditions that persist today. For some springs, the lack of even intermittent turbidity, low dissolved oxygen levels and water temperatures that lag seasonal air temperature variations suggest relatively long groundwater flow paths and residence times. With close fluorescent dye tracing difficult due to the sensitivity of the facility, we are now attempting to use natural tracers to further delineate the sources of these important waters.